Oenothera filiformis is a little-studied member of the plant family Onagraceae, a family whose reproduction systems are generally well-known. Flowers of O. filiformis appear to be night-adapted: they open at dusk, are white and scented. However, it is frequently visited by both a variety of moths at night, and honeybees (Apis mellifera) during the day. A pollen flow study was undertaken to better understand the pollination dynamics, and thus evolutionary pressures, of this species. Timed pollinator observations in the hours after sunset and sunrise were combined with counts of pollen stored on the bodies of captured specimens to produce a measure of pollen flow.
Results/Conclusions
It was determined that over 95% of the pollen flow could be attributed to the honeybees. However, because each fruit only contains 2-4 ovules, the relatively less efficient moths provide enough pollen to fertilize all or most ovules, so O. filiformis has adapted its floral traits to moth pollination. Preliminary data shows no appreciable difference in pollen tube formation in stigmas collected before or after honeybee visitation. Honeybees are generalist pollinators and are not native to North America, but O. filiformis is able to utilize them as a 'back-up' reproductive assurance in case of moth-poor seasons, and thus can be considered to have a bimodal pollination system.
